Drying apparatus for photographic sheet material

ABSTRACT

An elongated drying chamber is provided with transport means for carrying photographic sheet material edgewise with the sheets in end-to-end relationship past a plurality of tubes that issue drying air streams directed against the liquiphilic surface of the sheet material. The tubes are slotted a distance equal to substantially the full width of the sheet material for complete, gentle drying by sheets of air. A common plenum supplies the tubes with heated air; the air being directed from the tube slots at a pronounced angle to the sheet surface so as to provide for arraying the tubes close to the surface for maximum drying effect while minimizing the danger of mechanical interference between the edges of the sheets and the slots in the tubes. The drive for the transport is housed in an enclosure between the plenum and the drying chamber and is provided with access through an overlying insulating chamber; an air return duct being provided along another side to complete insulation of the drying chamber from ambient conditions. Discharge openings for release of moisture-laden air are the entrance and exit openings for the passage of said sheet material, and make-up air is drawn through a filtered inlet in the return duct.

United States Patent 1 Fletcher et al.

[451 Ju1yl0, 1973 DRYING APPARATUS FOR PHOTOGRAPHIC SHEET MATERIAL [76]Inventors: James C. Fletcher, Administrator of the National Aeronauticsand Space Administration with respect to an invention of; Paul Epstein,Brookline; George Donovan, Middleton, both of Mass.; Eric La White,Royalton, Vt.

[5 7 ABSTRACT An elongated drying chamber is provided with transportmeans for carrying photographic sheet material edgewise with the sheetsin end-to-end relationship past a plurality of tubes that issue dryingair streams directed against the liquiphilic surface of the sheetmaterial. The tubes are slotted a distance equal to substantially thefull width of the sheet material for complete, gentle drying by sheetsof air. A common plenum supplies the tubes with heated air; the airbeing directed from the tube slots at a pronounced angle to the sheetsurface so as to provide for arraying the tubes close to the surface formaximum drying effect while minimizing the danger of mechanicalinterference between the edges of the sheets and the slots in the tubes.The drive for the transport is housed in an enclosure between the plenumand the drying chamber and is provided with access through an overlyinginsulating chamber; an air return duct being provided along another sideto complete insulation of the drying chamber from ambient conditions.Discharge openings for release of moisture-laden air are the entranceand exit openings for the passage of said sheet material, and make-upair is drawn through a filtered inlet in the return duct.

11 Claims, 6 Drawing Figures I 'L l \9 DEYER TRAN 590m OUT 5a (6a HQ 1TRANSPORT SUPPLY TRANSPORT l'Z EXPOSE 1 DRYING APPARATUS FORPI-IOTOGRAPIIIC SHEET MATERIAL ORIGIN OF THE INVENTION The inventiondescribed herein was made in the per-- formance of work under a NASAcontract and is subject to the provisions of Section 305 of the NationalAeronautics and Space Act of 1958, Public Law 85-568 (72 Stat. 435; 42U.S.C. 2457).

FIELD OF INVENTION The present invention relates to drying apparatusand, more particularly, to a dryer adapted for acting on the liquiphilicsurface of photographic sheet material by heated air streams impingingupon said surface.

BACKGROUND OF THE INVENTION I It is known in the photographic field toprovide an apparatus for exposing a film, cutting the film to form afilm clip, transporting the film chip through a series of liquid bathsto develop the same and then drying the film chip, all in an automaticfashion without being touched by human hands. While these machines havebeen satisfactory and have represented great savings in terms ofeliminating the need for operators to handle and process the film, muchhas been left to be desired in terms of speeding the process to amaximum extent.

To explain, while the automatic transport of the film chip through thebaths satisfactorily saves processing time, heretofore, an efficientdrying apparatus to replace manual drying by hanging up of material haseluded what might be considered total success. In some cases, too rapiddrying occurs in the drying chambers which tends to burn or scorch thefilm thereby causing the film base, such as cellulose, to be subject topremature cracking, and thus rendering the same unuseable. This type ofshortcoming usually results from embodiments having radiant dryersplaced in direct proximity to the film or other sheet material of aphotographic nature, which on occasion causes hot spots to occur due tothe buildup of heat in the stagnant air between the heater and thesheet. I

The opposite effect of scorching of the film is insufficient drying whenthe film chip is ejected from the dryer in a still moist condition. Whenthe chip thus falls into the discharge hopper, it is subject towrinkling and distortion and is, of course, not subject to immediateprinting and storage. These previous machines have included blowing ofair streams, sometimes heated, across the surface of the film but withcertainly limited success in gaining a finished product that is assuredof being satisfactorily dried. These previous attempts have beencharacterized as also being extremely large and bulky.

OBJECTIVES OF THE INVENTION Thus, it is one object of the presentinvention to provide a drying apparatus for film chips, or otherphotograhic sheet material, that gains high efficiency in removingmoisture therefrom.

It is still another object of the present invention to provide anapparatus to dry photographic sheet material that removes moisture fromthe liquiphilic surface of the sheet material by a large number ofheated air streams impinging upon the sheet surface from orifices placedin close proximity thereto, thereby controllably drying said sheetmaterial.

It is still another object of the present invention to provide a dryingapparatus that is considerably reduced in size and power requirementsyet gives improved drying efficiency over previous attempts in thisfield.

BRIEF DESCRIPTION OF THE INVEN-TION' To briefly pinpoint some of themajor concepts in the drying apparatus of the present invention,reference must first be made to arrangements wherein film chips arecontinuously transported edgewise and dried. In these arrangements,drying should be in a rapid fashion but without scorching of therelatively delicate emulsion on the film that bears the image, as wellas without causing damage to the base material of the film itself. Thus,such a drying operation must be gentle, yet effective to removemoisture, and to do so under the most adverse conditions due to the factthat the emulsion is liquiphilic, that is, adapted to attract and retainmoisture. The machine must also remove moisture rapidly so that the chipmay be immediately used for printing of the picture. While film chipswill be discussed in the application to describe the inventive machineand its operation, it is to be understood that the apparatus is. equallyadaptable to other photographic processes, such as drying of a printsince essentially the same requirements of gentle, yet effective andrapid action are in effect.

Thus, the film chips are carried along by a continuous transport meansand a plurality of spaced dryer tubes having aperture means directedtoward the emulsion surface of the film chip are provided to ejectheated air .streams toward said surface.

The aperture means of the tubes is preferably a slot extending adistance equal to the full width of the sheet material so that dryingaction is gained uniformly over the complete surface area of the sheet.

The transport means must be driven, yet one side must be completelyaccessible for servicing and inspection of the transport path. At thesame time, it is desirable to have insultion around the drying chamberto minimize heat loss to the surrounding air. For these combinedreasons, the drive for the transport is situated between the dryingchamber and the air plenum. An insulating chamber extends along one sideof the drying chamber, plenum and drive enclosure for insulationpurposes and an air return duct extends along the same on an oppositeside for the same purpose. Discharge of moisture ladened air isadvantageously provided through the entrance and exit openings for thesheet material. An air inlet is provided along the air return duct forsupplying filtered make-up air.

For best results, the heater means is mounted in the plenum downstreamof the pressurizing fan and is situated so as to intercept the air flowfrom the pressurizing fan where the air velocity is high, therebyexpediting heat transfer from the heating means to the incoming air. Theplenum is thereby pressurized by heated air and so supplies all thedrying tubes to maintain substantially constant flow of heated air fromthe apertures along the drying chamber.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in this art from the followingdetailed description, wherein we have shown and described only thepreferred embodiment of the invention, simply by way of illustration ofthe best mode contemplated by us of carrying out our invention. As willbe realized, the invention is capable of other and differentembodiments, and its several details are capable of modification invarious obvious respects, all without departing from the invention.Accordingly, the drawings and description are to be regarded asillustrative in nature, and not as restrictrve.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic diagram showingan automatic film chip processor including a dryer transport sectionthat identifies the environments of the present inventron;

FIG. 2 is a front view of the apparatus showing the transport mechanism;

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG. 2 andshowing the preferred embodiment of the drying apparatus of the presentinvention in its most complete form;

FIGS. 4 and 4a illustrate the cross section through the dryer tubestaken along line 44 of FIG. 3 and showing the arrangement of theorifices and depicting the impingement of the air streams therefrom uponthe surface of the sheet material; and

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 3 andshowing the drying apparatus and transport mechanism from the top.

DETAILED DESCRIPTION OF THE INVENTION With reference now to FIG. 1 ofthe drawings, one environment in which the apparatus of the presentinvention may be successively utilized is shown. Thus, there isillustrated a film chip processor that supplies photographic film inroll form from film supply 11 to an exposure station indicated by thearrow 12, and thence through a cutter station 13 where a film chip isformed and fed into a first transport module 14. The film chip enters aprocessing section having individual processing modules l5, l6, 17 forimmersing each film chip into separate liquid baths. As shown, the bathsmay be held in a'segmented trough 18 that is capable of being lowered toan inopertive position for shutdown and cleaning purposes. Each module15l7 is provided with a corresponding wringer module 15a, 16a, 17a toremove the excess liquid rom the film chip after each bath. Afterleaving the final wringer module 17a, the film chip enters finaltransport module 19 and is delivered to a combination dryer-transport,generally designated by the reference numeral 20, and to which thepresent invention is directed.

Upon leaving the dryer-transport 20, the film chip is expelled in acompletely developed and dried state to a suitable discharge station 21.It will be realized that insofar as the features of the inventivedryer-transport 20 are concerned, the processor 10 could just as well bea printer of photographic paper, whereupon the exposure station 12 wouldbecome a printing station and the film chip would more accurately bereferred to as a photographic print. Thus, the film chip processor 10has been selected merely to show an environment and a suitable operativeor preferred form of the invention, and it is therefore to be understoodthat the drying apparatus of the invention has utility in both thedeveloping and printing aspects of the photographic field.

In FIG. 2, the front view of the dryer-transport 20 is illustrated withadjacent parts broken away for clarity. Suffice it to say that a filmchip leaving the engagement of opposed transfer belts 25, 26 of thefinal transport module 19 are directed in accordance with the arrowbetween opposed transport belts 27, 28 that are made up of a pluralityof belt sections (see FIGS. 3 and 5) grasp the film chip by its sidemargins and to hold the film chip (see dotted line outline F in FIG. 5)therebetween and convey the same in continuous motion along an elongateddrying chamber 30. 1

As shown in FIG. 3, the drying chamber 30 is effectively closed by atransparent door 31 having a suitable latch 32 thereon; the film chips Falong the transport path thus being easily viewed by the machineoperator and easily accessible in the event of ajam up or prematureshutdown of the machine. The chamber 30 is formed on other sides by atop wall 33, a rear wall 34, a bottom wall 35, and two end walls 36, 37,as shown in FIGS. 2 and 3.

Certain of the belt sections of upper and lower transport belts 27, 28are driven by spools 40, 41 through drive shafts 42 extending throughrear wall 34 (see FIGS. 3 and 5). The shafts 42 are positioned within adrive enclosure 43 and receive motive power from a longitudinallyextending worm 44, in turn driven by a belt drive 45 and main motor 46.

The manner in which the film chips F are dried as they move along thedrying chamber 30 will now be described, having reference to FIGS. 2-4.Thus, a plurality of dryer tubes are spaced in close proximity to eachother along the chamber 30 and extend therethrough. The dryer tubes 50enter the drying chamber 30 after traversing the drive enclosure 43 andreceive heated air from a plenum 51 just to the rear of said driveenclosure 43. Each tube is provided with a mouth 52 opening directlyinto the elongated plenum 51 and each is provided at the opposite end inthe drying chamber 30 with an elongated slot 53 for release of the airinto operative working engagement with the film chip F. As shown in FIG.3, thevslot 53 extends substan tially across the full width betweenthebelts 27, 28 so that the film chip F is dried across the full widththereof.

In accordance with the invention, the slots 53a, 53b,

I 53c, 53d of adjacent tubes 50 (FIG. 4) are directed toward theemulsion coated surface S of the film chip F. These slots 53a, 53b, 53cand 53d issue air streams in the form of flat sheets which impinge uponthe surface S, as shown by the dashed line arrows of FIG. 4. FIG. 4ashows a similar arrangement, but representing the angular arrangement ofslots and air streams presently preferred.

The significance of the arrangement shown is in the close proximity ofthe drying tube apertures to each other and to the emulsion surface ofthe film, so that the drying air impinges upon the emulsion while theair velocity is still relatively high, thereby effectively penetratingand displacing the layer of moisture-laden air next to the emulsionsurface. Also, by providing a large number of tubes 50 in closeproximity to each other, the arrangement provides a maximum number ofsuch air streams in a minimum space, and arrayed in such fashion thatthey contribute to a compact and yet simple and reliable transport path.By this it is meant that the resulting transport path is not only quiteshort for practical convenience, but also has no sharp bends which mighttend to cause the film chips to buckle during travel, whereby the chancefor interference between the edges of the film chips and the tubes 50(with possible jams as a result) is removed. In addition the angulardisposition of the slots 53 places their edges out of reach of the filmchip edges even if a sheet should occasionally buckle sufficiently tocontact the bottom of a tube. For best results the angular dispositionof the slots should be so as to place their edges well above the tubebottom. At least a degree angular displacement from the vertical shouldbe used, and a 45 angle is presently preferred.

The air pressure also causes air flow around the ends of the film chip F(as denoted by the arrows 55, 56 in FIG. 4) so that the bottom, which ofcourse carries much less moisture anyway, is also assured of beingdried, and that portion of the air not exhausted by way of entrance andexit openings 80, 81 hereinafter described, is eventually moved towardexit openings 57 in the bottom wall 35 and into duct 58.

A temperature sensing element 100 extending into the drying chamber 30is used to control, by any of well known power controlling devices notshown, the power supplied to certain heating units, to be identifiedhereinafter, thereby regulating the temperature of the air in saiddrying chamber. This allows the temperature of the drying air to beselected by the machine operator to suit the particular conditionsencountered. In this way, the heaters are supplied with only sufficientpower to maintain the selected temperature, thereby reducing wastedpower and preventing the temperature of the air in the drying chamberfrom increasing to a degree where the film chip may suffer damage.

As previously indicated, a substantial portion of the air from dryingchamber 30 is returned through air return duct 58, accelerated by twofans.60, 61 (see FIGS. 3 and 5), and thus, returned under pressure tothe plenum 51. The fans 60, 61 are supported by spider elements 62 fromfan housings 102. On an elongated asbestos plate 70, carried by suitableupstanding studs 71 from fan housings 102, there are provided in theareas immediately above the fans 60, 61, electrical resistance heatingunits 72, 73, :hereinbefore referred to, that supply the heat to the airfor drying the sheet material. Since the heating elements 72, 73 arethus downstream of the fans 60, 61, the air isforced thereacross atrelatively high velocity for the most expeditious heat transferrelationship.

The plenum 51 is thereby filled with pressurized and heated air tosupply the mouths 52 of the drier tubes 50.

Also, in accordance with the invention, the heater units 72, 73 and thecooperating fans 60, 61 are spaced along the elongated plenum 51. Thus,the air in the plenum is more uniformly pressurized and heated, therebysupplying all the mouths of the heating tubes substantially equally, toprovide a more beneficial drying action.

Since the majority of the air is returned or recirculated from thedrying chamber 30 to form substantially a closed circuit, the powerrequirements for the heating units 72, 73 are substantially reduced.This is particularly important in a unit of this type whereinintermittent operation is common and thus rapid heating of the dryingair on initial start-up is required. Thus, when a first film chip in aseries is exposed at station 12, the heating units 72, 73 and fans 60,61 may be turned on then and by the time that the film chip has reachedthe dryer-transport 20, the air has been heated sufficiently to dry thefilm chip. This cumulative effect of heating the air by recirculation ofpreheated air allows the heating units 72, 73 to be of minimum capacity,conserves space, and gives an obvious reduction in initial cost of theapparatus.

Since moisture is constantly being taken up by the circulating air, itis important to release a portion thereof during normal operation. Thisis advantageously done in the present arrangement through entrance andexit openings 80, 81 formed in end walls 36, 37 (see FIG. 2) throughwhich the film chips F respectively enter and leave the drying chamber30. No additional exhaust port is needed in order to expel themoisture-ladened air, and as such the conservation of heat in the unitthrough recirculation just described is maximized.

The necessary make-up air for the air exhausted through the openings 80,81 is introduced through a filter 85 and slotted openings 86 in the airreturn duct 58. The filter 85 prevents foreign matter from entering thesystem, and thus from being deposited on the film chips F; it beingunderstood that all other potential openings to this substantiallyclosed system are blocked against outgoing air flow during operation.

The retention of heat in the chamber 30 is further enhanced by providingwarm air containing chambers along the bottom, that is, air return duct58; along the back, drive enclosure 43; and along the top, insulatingchamber 90. Thus, not only is direct transfer of the heated air from theclosed system limited, but also the radiant transfer of heat isrestricted.

Access to gears 44, 47 for inspection, lubrication, etc. can be readilyhad through openings 91 and 92 without affecting significantly the heatpreservation integrity of the insulating chamber 90, and housing of thedrive gearing so as to prevent any air exchange with the drying chamber30 minimizes the danger for contamination of the work.

In summary, the present invention provides a drying arrangement whereinthe moisture is more efficiently removed from photographic sheetmaterial by a plurality of sheet-like air streams impinging uponthe'emulsion bearing surface of said sheet material. The dryerapparatus'is of a compact design due to the method of placement of theapertures supplying the air streams in close proximity to the emulsionside of the sheet material, but in such a way as to prevent interferenceand jams. Furthermore, heat is conserved by recirculation of the bulk ofthe air and exhausting only through the entrance and exit openings 80,81. The plenum 51 is designed with heating units 72, 73 so as toefficiently distribute the air uniformly into the mouths of dryer tubes50, that in turn, release the heated air into the drying chamber 30. Airreturn duct 58, drive enclosure 43 and the insulating chamber 90, limitloss of heat.

In this disclosure, there is shown and described only the preferredembodiment of the invention, but, as aforementioned, is to be understoodthat the invention is capable of various changes or modifications withinthe scope of the inventive concept as expressed herein.

We claim:

1. An apparatus for drying photographic sheet material previouslyprocessed in liquids and having a liquiphilic coated surface comprisinga drying chamber, transport means for supporting said sheet material andmoving the same edgewise continuously through said chamber, a pluralityof spaced dryer tubes extending into said chamber, aperture means insaid tubes opening adjacent and directed toward said surface fordirecting drying air streams against said sheet material on saidtransport means, an air plenum connected to said tubes, heater means forair, fan means for affording pressure to said air in said plenum andforcing the heated air through said tubes and out said apertures, anddrive means for said transport means in a drive enclosure interposedbetween said plenum and said chamber, said drive enclosure acting toprotect against possible contamination of the drying air chamber.

2. The drying apparatus of claim 1 wherein the apertures are sopositioned that the air streams are directed at an angle to the sheetsurface.

3. The drying apparatus of claim 2 wherein said aperture means comprisea slot on each tube extending a distance equal to substantially the fullwidth of said material for complete drying thereof.

4. The drying apparatus of claim 1 wherein said dryer tubes traversesaid drive enclosure.

5. The drying apparatus of claim 1 wherein said drying chamber isprovided with discharge openings for release of moisture-ladened air,said openings being positioned at the entrance and exit to saidtransport from contacting said sheet material. 7. The drying apparatusof claim 5 wherein said heater means are mounted in said plenum, saidfan being mounted upstream of said heater in said plenum to direct airagainst the same to receive the heat.

8. The drying apparatus of claim 7 wherein said plenum is elongated,extending substantially along the length of said chamber.

9. The drying apparatus of claim 8 wherein said heater means includes aplurality of heating units spaced from each other and the ends of saidplenum, whereby heated air is directed generally along the longitudinalaxis of said plenum and into the mouths of the tubes, whereby theheating effect is substantially constant along the length of' saiddrying chamber.

10. The drying apparatus of claim 9 wherein is provided an air returnduct connecting said chamber to said plenum along the length of both forsubstantially constant flow and to insulate the same against ambientconditionsto conserve heat.

11. The drying apparatus of claim 1 which further includes an insulatingchamber extending across one side of said drying chamber, an airexchange duct extending across another side of said chamber, and inwhich said insulating chamber, said air exchange duct, said plenum, andsaid enclosure, act to insulate the drying chamber againstambientconditions to conserve heat.

1. An apparatus for drying photographic sheet material previouslyprocessed in liquids and having a liquiphilic coated surface comprisinga drying chamber, transport means for supporting said sheet material andmoving the same edgewise continuously through said chamber, a pluralityof spaced dryer tubes extending into said chamber, aperture means insaid tubes opening adjacent and directed toward said surface fordirecting drying air streams against said sheet material on saidtransport means, an air plenum connected to said tubes, heater means forair, fan means for affording pressure to said air in said plenum andforcing the heated air through said tubes and out said apertures, anddrive means for said transport means in a drive enclosure interposedbetween said plenum and said chamber, said drive enclosure acting toprotect against possible contamination of the drying air chamber.
 2. Thedrying apparatus of claim 1 wherein the apertures are so positioned thatthe air streams are directed at an angle to the sheet surface.
 3. Thedrying apparatus of claim 2 wherein said aperture means comprise a sloton each tube extending a distance equal to substantially the full widthof said material for complete drying thereof.
 4. The drying apparatus ofclaim 1 wherein said dryer tubes traverse said drive enclosure.
 5. Thedrying apparatus of claim 1 wherein said drying chamber is provided withdischarge openings for release of moisture-ladened air, said openingsbeing positioned at the entrance and exit to said transport means andallowing passage of said sheet material, and an air inlet communicatingwith said plenum for supplying make-up air.
 6. The drying apparatus ofclaim 5 wherein said inlet is provided with filter means to preventforeign matter from contacting said sheet material.
 7. The dryingapparatus of claim 5 wherein said heater means are mounted in saidplenum, said fan being mounted upstream of said heater in said plenum todirect air against the same to receive the heat.
 8. The drying apparatusof claim 7 wherein said plenum is elongated, extending substantiallyalong the length of said chamber.
 9. The drying apparatus of claim 8wherein said heater means includes a plurality of heating units spacedfrom each other and the ends of said plenum, whereby heated air isdirected generally along the longitudinal axis of said plenum and intothe mouths of the tubes, whereby the heating effect is substantiallyconstant along the length of said drying chamber.
 10. The dryingapparatus of claim 9 wherein is provided an air return duct connectingsaid chamber to said plenum along the length of both for substantiallyconstant flow and to insulate the same against ambient conditions toconserve heat.
 11. The drying apparatus of claim 1 which furtherincludes an insulating chamber extending across one side of said dryingchamber, an air exchange duct extending across another side of saidchamber, and in which said insulating chamber, said air exchange duct,said plenum, and said enclosure, act to insulate the drying chamberagainst ambient conditions to conserve heat.